My dog has mixed feelings about fireworks?

My dog has a fit every time she hears a firework. She will wag her tail like she is happy. She will whine and shake like she is scared. She will bark very loud like she is trying to warn someone about something. She will growl like she is angry. And lastly, she will pant like she is hot. She will be doing all of this stuff when she hears firecrackers, especially the screaming kind. One time, we had her out on a leash while we were lighting some. We had lit one of those display fountain firecrackers. She accually broke off the leash and attemped to attack the firecracker while is was working! Now of course we keep her inside when we light them. If kids use sparklers near her, she will growl at the sparkler. If you bring it down to her level, she will snap at it. It's kind of scary in a way. Why does she feel like she has to do this when she hears them or sees them? I mean I'll be playing a game that has them as a sound effect and she'll have a fit. What can I do about it? Thanks!